It took a while to get started on this review for a few reasons. LEAR graciously supplied me with the standard cable AND the upgrade cable (NSC-03) for the NS-U1, which have Natrosound on and off switches so in a way I had several reviews and comparisons to do. Not that I am complaining mind.

The LEAR NS-U1 is a concept piece in itself which a quick browse of their website will reveal in detail about the ideas and design behind the seed to fruition of this IEM.

They describe it best so to save you a link click I have copied the relevant information over for you, its a good introduction to the concept before we get into the review.

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From the webpage:​

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"LEAR's NS technology makes earphones simulate the loudspeakers' natural hearing experience. With NS, users can experience a natural front audio image with current audio files, without any additional plug-ins or external power! A lot of users feel uncomfortable, some to an extent that they get a headache because of traditional earphones' stereo sound.​

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The sound on both loudspeakers are received by both our ears, and our ears determine the distance from the sound source with this effect.​

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The sound on a pair of headphones come with separate channels like loudspeakers. As the sound of headphones direct to one ear at a time, the ear would not receive the sound from the opposite channel. This results in an unnatural sound, which some might feel uncomfortable with this 'inside the head' sound effect that is different from the real world.​

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The NS simulates a sound closer to the natural and actual sound from the real world.​

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The NS technology sends the sound from opposite channel to the opposite earphone, in which NS acoustically simulates the natural sound delay and level. Consequently, user can experience the normal loudspeakers sound with NS.The NS technology sends the sound from opposite channel to the opposite earphone, in which NS acoustically simulates the natural sound delay and level. Consequently, user can experience the normal loudspeakers sound with NS.​

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Some might link to Crossfeed and relates electronics/softwares/DSP products, but LEAR's NS technology is the world's first acoustical HRTF simulation earphones technology, which features are listed below:​

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Internal structure of NS-U1​

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No external software/hardware, electronics, or external power needed: plug the NS earphones into any mobile/player and that's it!"​

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Build

The build of the NS-U1 is mysterious as the shells are bulbous and quite different to what I am usually accustomed to seeing in an IEM.
Nonetheless the shells and housing are solid, the cable is very robust.
Two dynamic drivers are in each ear piece.
The nozzle is long and therefore will easily access most ear canals.

Two cables seen here: on the left the after market cable LEAR NSC-03 (kindly included by LEAR for review) and on the right the usual bundled cable that you would get with the NS-U1.​

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NOTE: the four pin design which is a key to how these IEMs work by turning on or off the extra driver.​

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As can be seen the cable carries a four pin design,​

as opposed to the usually two pin or MMCX connectors.​

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A simple no fuss nub for connecting the tips.​

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Tips and connectors fit without effort.​

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Packaging

The packaging is of an appropriate size. Not too big, nor too small.

Two thirds contain the round case and IEMs, the cardboard square box the added tips and manual etc.

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It comes with a sturdy case that has a black hard exterior and a green rubber interior for extra protection.

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Stock cable.​

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Fit

The fit on the LEAR NS-U1 can be comfortable even though the shells are quite large and bulbous.
A stronger memory wire would have helped with the fit and keeping them fixed in place. I suspect the longer connector housing has something to do with that, as it prevents a nice form fitting curve around the top front of the ear.
They would tend to go from a good fit to sometimes popping out at first, one has to get the right angle and cable tension to achieve no movement then they seem to be ok.
Good isolation and balance between both ends as far as sound is concerned.

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Sound

The sound for this review is mainly separated into several parts due to the two cables and also the different settings on the two cables.

NOTE: There is a difference between the first impressions straight from the ipod touch to my later experiments with the Centrance Hifi-Skyn.

*The stock cable has a on/off switch for the Natrosound, a microphone for taking phone calls.

*The upgrade cable has the Natrosound on/switch and also bass and dials to increase/decrease the bass or the Natrosound.

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LEAR NSC-03 upgrade cable.​

Note the bass and Natrosound gradual adjuster dials on the left side.​

Stock cable. More light and airy without the Natrosound on, seems recessed, with the Natrosound on more bass and low end..fuller sound overall, smoother. Mids are too forward.

Upgrade cable

LEAR NSC-03​

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Natrosound off, thin sound, although improved with bass set at near full.
Natrosound on. Fuller sound, like an extra speaker underneath it all, bass off, I turned down the Natrosound a tad and better clarity was achieved.

Summary: With either cable there is sometimes slight distortion with the Natrosound on at high volumes, also can sound a bit airy/empty without it turned on with some tracks.
With Natrosound turned on at moderate volumes it is an enjoyable experience. Very nice to listen to and largely smooth overall, non fatiguing.
Either setting it has a fast response.

Improved fidelity and smoothness overall.
The NS-U1 seems to enjoy the extra gain and power.

Listening with the stock cable has turned into a more pleasurable experience, even with the Natrosound turned off. Smooth, full, even.
With the Natrosound turned on it seems at first like a slight improvement, a small jump, more fuller, rounded bass, but when I switch back and forth I am able to appreciate more what the Natrosound actually does and it is quite wonderful. Some detail is lost. Soundstage is fuller and wider.

But of course the limitation is within the on/off of the Natrosound itself with the stock cable.

Back to the upgrade cable LEAR NSC-03.

Natrosound off.
Nice and clear, nothing exciting, fairly flat and reference. Clear. A sound signature that I could enjoy at low volumes. too much volume can give peaky treble.

Natrosound on. bass off.
Congested at first until I adjusted the Natrosound dial a bit by turning it down a tad.
Clear and nice with good details, ok soundstage. More height than width.
Adding a bit more bass by way of the detail gives it an nice warmth and intimacy which balances out the highs somewhat.

The concept is basically a type of crossfeed in some ways, although not exactly that, the sound from the main driver is fed into the smaller driver on the opposite side to give a more balanced result from the music.

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Value

HK$1,688.00
or US$ 217.00.
Not a TOTL IEM price, but just above budget prices.
The LEAR NS-U1 fits into its price point well, good packaging and extras.

It is a concept piece in a way so it depends on whether that floats your boat.
If you are into crossfeed or non fatigue then this would be for you.

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Overall
The LEAR Natrosound NS-U1 is a certain IEM for a certain someone.
At US$217 at the time of writing is a lower to mid fi price, either for someone nervously shopping around for the best of what their money can offer, or for some daddy more bucks who just wants to try it out for fun.
The build is solid and sturdy, perhaps too sturdy in places as the cable is a bit hard to fit snugly around the ears, and the connector is quite long, but aside from that I could still get a satisfactory fit and seal with minimal pop outs from the ear canal.
The sound differs from the stock to the better upgrade cable and is a matter of taste.
I preferred the upgrade cable

LEAR NSC-03 ​

the Natrosound turned on (with dial adjustments), the added options to adjust the sound and fine tune the experience improves it overall.
Experience differs with the music playing also, the LEAR NS-U1 seems to favor more quiet and laid back music, heavy rock at times can be hard for them to handle and gets congested.
Sound reproduction is generally realistic and accurate.

With the stock cable I prefer the Natrosound off, with the upgrade cable I prefer the Natrosound on (with adjustments to the dials).

In short it does take some adjusting to get used to the Natrosound but once I did i quite enjoyed it and it grew on me over time.

Cons - sound w/ standard cable imho so-so with enabled NS, not for small ears, ear guides could be more flexible

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Preamble:

Before I move over to my preamble, I’d like to give out a warm thank to Tatco Ma, the man behind LEAR, for providing me with a sample of the updated NS-U1 in-ears and NSC-03 cable free of charge in exchange for my honest, unbiased opinion.

LEAR, founded 2008 in Hong Kong by the Hong Kong Forever Source Digital, one of the most well-known local professional portable audio products, quickly got attention and good reputation in international audiophile circles. For good reason, as in 2014, their hard and consequent work was awarded by the renowned international business magazine publisher Mediazone with the “Hong Kong's Most Valuable Companies Award 2015”.

Early in 2015, I got aware of the NS-U1 (by then yet known as NSS-U1) through this YouTube video made by LEAR: https://www.youtube.com/watch?v=eNYQWvuhPWU
Actually, I could just finish my preamble right now, as Tatco’s excellent video perfectly explains and demonstrates what NatroSound™ is and does.
The main principle NatroSound is based on is crossfeed. For those who aren’t yet aware of what crossfeed is, let me explain it to you with this commonly used example: Listening to music through loudspeakers, the right ear doesn’t only get the sound from the right speaker, but also from the left (with a minimal time delay). The same goes for the left ear that is also reached by the right speaker’s sound waves and not only the left’s. With headphones, this effect gets lost and tones that are mixed only to the left channel will not be heard by both ears (which would be the case with speakers), but only with one. This is also the main reason why some recordings (the ones by the Beatles are a paramount example of ping-pong stereophony) can sound somewhat artificial through headphones and why the soundstage is mostly rather inside instead of more in front of one’s head.
For this scenario, crossfeed was developed – very simplified speaking, some of the left signal gets mixed to the right channel and vice versa (of course there are also more things involved like for example transit time delay compensation), to mimic a speaker-setup’s soundstage-related listening impression. In the NS-U1, acoustical crossfeed is implemented by the use of two dynamic micro-drivers per side with a specific tube system for the NS driver.

I have to honestly admit that I am a crossfeed-sceptic and that it mostly doesn’t show much effect in my ears, but that is something that varies among individuals. Hardware-based crossfeed solutions like those by Meier or SPL could just moderately convince me (although the Phonitor 2 has got many possibilities for fine-adjusting the crossfeed, it didn’t appear 100% natural to me and additionally I perceived the amplifier section as a little sound-degrading), software-based implementations didn’t show any effect at all for me. The best crossfeed implementation I heard to date was ifi Audio’s.

Well, let’s see whether and to what extent the revised version of the NS-U1 and especially its NatroSound can manage to convince me.

The NS-U1 arrives in a LEAR-typical black cardboard box that however shows a silhouette of the NatroSound in-ears on the lid, along with the LEAR as well as NatroSound and NS-U1 logos.
Taking off this lid, one will find LEAR’s very convenient threaded protective case with inner green rubber bolstering, next to a small black box with LEAR logo that contains an instruction manual, two pairs of single-flange silicone tips (the third pair in M size is already installed) and last but not least two pairs of foam tips.

The additional NSC-03 cable was included in my evaluation sample as well.

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Looks, Feels, Build Quality:

The in-ears that are available in two different glossy metallic colour schemes (blue-black or grey-black (old version with different tuning: chrome-black)) are quite large and bulky. The colours nicely fade into each other, giving a nice visual appearance; the outer half of the shell shows a LEAR logo, the inner the side markers. The shells seem pretty well made (that small uneven gap on the right side will be corrected with the second production batch) and appear very sturdy.

The standard cable is somewhat rubbery but also seems very sturdy, even for tough use. The strain relief is excellent on all transitions; the very thin 3.5 mm connector is angled and made of metal.
Above the y-split that contains the NatroSound switch is a good one-button remote control with integrated microphone on the right side, a cable cinch is unfortunately missing.
The NSC-03 cable is actually identical to the standard one, but has got a cable cinch (although it is rather loosely fitting, it works just perfectly as it should) and lacks a remote control. Instead, the y-split is larger and features each a potentiometer for adjusting the intensity of the NS and bass (the latter also when NS is deactivated) next to the NatroSound switch.
Both cables have got 4-pin connectors (two pins for each driver).

The ear guides with built-in memory wire aren’t as good to mould and shape as those from other in-ears. Hence, with the addition of the missing cable cinch of the NSC-01 cable, microphonics are somewhat higher than they could be with this around-the-ears fit (microphonics aren’t super bad but still only average though).
With the NSC-03 cable, microphonics are a bit lower due to the cable cinch, but could still be slightly better with other ear guides that have better mouldable memory wire.
As the in-ears are pretty large and bulky, one should best have at least averagely large ears for a good fit. I with my large auricles don’t have any comfort or fit issues with the NS-U1.

The in-ears’ back has got a tiny vent, nonetheless isolation is better than just average and actually quite good, however not yet reaching closed in-ears’ levels.

Sound:

For listening, I mainly used the Leckerton UHA-6S.MKII, LH Labs Geek Out IEM 100, my music-playback optimised iPhone 4 as well as iBasso DX90 and DX80. Occasionally I also used my FiiO X3.
Just as usual, I used the largest included single-flange silicone tips.
Although I am no burn-in person, I played 50 hours of white noise and sine sweeps before even starting casual listening (just in case).

Tonality:

NSC-01 Cable:

NatroSound disabled:
Tonally, NS-U1’s midrange and treble are pretty balanced sounding, with some extra boost in the midbass and especially sub-bass.
Chapeau, Tatco, the integration of the sub-bass emphasis is very well made and really mainly concentrates on the lowest frequencies, in contrast to most other bass-emphasised in-ears that also feature ample upper bass and fundamental tone, making the lower registers unnecessarily thick, warm and boomy.
At around 500 Hz, the LEAR’s bass starts evenly rising in a straight line and reaches its climax around 85 Hz with about +11 dB compared to a strictly flat in-ear like the Etymotic ER-4S, keeping this level upright down to 20 Hz without roll-off – this low climax around 85 Hz is an important thing for a bass emphasis with its main emphasis on the mid- as well as sub-bass. Because of this really low sitting climax (with many in-ears, it is between 100 and 200 Hz), there is no real fundamental bloom, wherefore neither unnecessary warmth nor thickness in the root is present. As a matter of that, the upper bass hits firmly and mid- as well as sub-bass show an ample amount of rumble without appearing overdone at all.
From 1 to 4 kHz, I hear an evenly rising level when using sine generator software, wherefore vocals are minimally on the brighter and thinner side, though still tonally pretty correctly sounding in my ears (this moderate emphasis harmonises well with my HRTF). Right afterwards, the level goes back to a normal level again, slightly sinks below ground-line and comes back to roll rather quickly off above 10 kHz – one shouldn’t expect too much subtle super-treble glare above 10 kHz.

The bass emphasis is set low enough to neither fatten the sound nor being annoying (and therefore doesn’t only offer ample mid- and sub-bass levels but also a good compensation for the lower frequency masking by noise present when using public transport), the mids are tonally pretty correct, the treble is relatively even and the whole sound is quite natural, with just minute metallic-ness with hi-hats and trumpets due to the moderate emphasis towards 4 kHz.

NatroSound enabled:
Midrange and treble levels don’t really seem to be affected, however there is some change going on in the bass and fundamental regions: although the climax is still being reached below 100 Hz, the emphasis is a bit stronger and the root clearly gains warmth and body because of stopping not until 800 Hz (NS disabled: 500 Hz). As a result, vocals are now on the meatier, warmer side and gain some muffled tendency.

NSC-03 Cable:

NatroSound disabled:
The main advantage over the regular cable is the ability to adjust bass quantity. As for this, the sound can reach from “bass-shy and mid-centric”, “quite neutral” and “balanced midrange and treble with sub-bass emphasis à la NSC-01 but with a bit more fundamental warmth”.

NatroSound enabled:
The root and lower mids also gain more warmth, but this can be regulated really well to tonally correct mids as long as the bass pot is not at the max position and the NS pot is neither. For bass and NS quantity to one’s personal preference, the NSC-03 cable is really suitable.

Resolution:

NSC-01 Cable:

NatroSound disabled:
The NS-U1 does a good job for an in-ear with dynamic drivers and somewhat surpasses some other dynamic driver in-ears in the same price range (comparisons further below) in terms of realism and control, despite not quite reaching the LEAR LHF-AE1d’s strengths in some areas, my dynamic driver reference in-ear in the price range around $200.
The bass is pretty quick, arid, controlled and precise for a dynamic driver, with firm and quick upper bass (the use of a small 6 mm micro-driver is really paying off) as well as well controlled sub-bass that is however slightly softer than the upper bass but no less controlled.
Midrange and treble sound realistic, with a good and overall natural presentation of the upper frequencies, though I wouldn’t mind just a pinch more midrange details, however only when comparing the NS-U1 to the LHF-AE1d.
What I’m hearing is really well-made and when the LHF-AE1d is considered as the king, the NS-U1 could be considered as the young prince with its dynamic, quick bass.

NatroSound enabled:
The monarchy is starting to crumble and the prince has to fear for his position in the direct line of the throne: with activated NatroSound in combination with the standard cable NSC-01, the bass appears softer, the mids sound somewhat coated, the treble veiled, and I don’t buy into the greater bass body presence (it just doesn’t appear natural to me, somehow compressed). Compared to disabled NS, the NS-U1’s sound appears coarser and not as refined or precise anymore, which is also because of the different spatial presentation. A decadence from aristocracy to upper class.
For the pure resolution, I surely wouldn’t use the NSC-01’s NatroSound feature.

NSC-03 Cable:

NatroSound disabled:
The resolution remains identical to the NSC-01 cable, however with a slightly more arid bass when one reduces its quantity with the potentiometer.

NatroSound enabled:
When the bass potentiometer is just sparsely used and in use to lower quantity, the dynamic 6 mm driver is less strained which is also audible – the resolution is almost identical to the NSC-03’s cable with deactivated NatroSound (so he said and put the standard NSC-01 cable back into the box with the intention not to use it anymore in the next time, at least not for NatroSound, as he loved the NSC-03’s cable’s ability to strain the drivers less).

Soundstage:

NSC-01 Cable:

NatroSound disabled:
Even with disabled NatroSound switch, the in-ear’s soundstage is better than average in terms of expansion to the sides and depth, with a plausibly appearing imaginary field of sound. The positioning of instruments in this imaginary room seems authentic as well, with good separation for an in-ear with dynamic drivers for that price, although some better BA-based multi-driver in-ears around $200 have sharper instrument separation. Although there is slightly less depth than width, instrument layering is quite well presented.

NatroSound enabled:
With enabled NS, the soundstage gains both more intimacy as well as more spatial depth, with somewhat less perceived width due to the gain of depth. In most cases, the front projection really leaves my head, but at the cost of instrument placement- and separation precision that seem somewhat foggier.
A few comments regarding the NS-effect’s naturalness: with many recordings (especially old and many modern ones that were mainly created the with the computer), the soundstage seems somewhat more authentic (many Beatles recordings with ping-pong stereophony effect mastering have finally become bearable with these in-ears), with some others the authenticity remains identical compared to disabled NS (but with a different presentation), and with few recordings, the NatroSound effect sounds slightly less authentic in my ears, but that’s just in the minority of the cases – most of the times, the spatial presentation with enabled NatroSound appears more plausible, especially when directly compared to when the switch is in “OFF” position and one suddenly gets the feeling that the imaginary room is flatter, with something somehow missing.

NSC-03 Cable:

NatroSound disabled:
Taming the bass a little and bringing it closer to a neutral level, the instrument separation as well as placement gain precision and tonal elements are more precisely positioned in the imaginary room compared to the NSC-01 cable with disabled NatroSound.

NatroSound enabled:
With also reduced bass quantity, the soundstage appears both deeper as well as clearly more precisely layered in my ears than with enabled NS with the NSC-01 cable. To my surprise, the soundstage width with the NSC-03 cable and engaged NatroSound isn’t really narrower in my ears compared to the same cable with disabled NS, as long as the NS potentiometer isn’t turned up to the max. Although the instrument separation sharpness is slightly less clean than with disabled NSC-03 NatroSound, this difference is much smaller than with the NSC-01 cable.
And because of all of that, the spatial presentation is very enjoyable, better forward-projected and more precise.

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On a personal editorial side-note: Just as mentioned at the beginning in the preamble, I am no 100% convinced crossfeed devotee. This also doesn’t change entirely with NatroSound, but what I have noticed is that with engaged NS while listening, I experience much less ear fatigue and that the music sounds more real to my brain, wherefore it has to “work” and concentrate less. Especially with the NSC-03 cable where I can eliminate the occurring fattening of the midrange with enabled NatroSound, the spatial impression appears somewhat more natural. In the end, except for the essential sound descriptions with the NSC-01 cable, I actually only used the NSC-03 with enabled NS for “private/casual listening”, as it offers the huge benefit of adjusting the NatroSound effects as well as the sound’s fullness to one’s personal preferences.
Because of the clearly reduced listening fatigue with enabled NatroSound for me, I also noticed that watching TV shows or films with the NS-U1 is somewhat more relaxed and pleasant.

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In Comparison with other In-Ears (mainly used the NSC-03 cable for comparison):

Sennheiser IE 80:
On the technical side, the IE 80 is a comparatively rather average dynamic driver in-ear whose strength lays mainly in its soundstage rendering as well as smooth, even sound, wherefore it is well-suited for slow and acoustic recordings, where it does its job quite well in my opinion (Metal or fast Electro recordings don’t really suit the IE 80 much).
With fast music, the NS-U1 clearly manages to keep the better control and sounds audibly less muddy, as its bass is quicker plus better controlled, even when NatroSound is engaged by ~ 80% and even when set to 100%.
The logical result was that I then mainly tested and compared the two with rather slow tracks, to give the Sennheiser more chances.
Nonetheless, the LEAR sounds quicker, cleaner and more detailed, with the better reproduction of singers’ variations and minute treble details.
In terms of soundstage, both in-ears are much closer than one could think based on the past few lines. With deactivated NatroSound, the Sennheiser’s soundstage appears more spacious, more distant and deeper. With engaged NS, the NS-U1 is better at conveying a realistic impression of mellowness/closeness and depth, and the soundstage also appears more harmonious plus the LEAR has the sharper instrument separation as well as placement; tonal elements seem to be more in an orbit in front and around the head.

RHA T20:
The LEAR has got the somewhat faster, but especially better controlled bass (the RHA sometimes appears somewhat blunt and has somewhat too much rumble in the bass, lacking some control with complex bass lines).
Also when it is about general resolution, the NS-U1 is the winner, putting out some more details in the midrange and treble, although the differences aren’t night and day.
Without NatroSound, soundstage size of both in-ears is about identical and the spatial precision remains on-par as well (as long as no tracks with fast bass strokes are played, as then the LEAR is the winner). Enabling NatroSound, the NS-U1’s projection of closeness is better and it generates the deeper stage with more precise layering.

Echobox Finder X1:
The victory in the category of bass speed (NSC-03 with maximum bass, no NatroSound) is the Finder’s, however it is a close one. In terms of bass control however, both in-ears are about on the same level and the LEAR shows the identical amount of details in the bass.
When it is about overall resolution in general, the NS-U1 is the winner as well (nonetheless again not by much, only by a razor blade’s thickness), by sounding very slightly more detailed in the mids and treble.
What the LEAR however does better by a certain degree are things like naturalness of its sound presentation (I don’t blame the Finder for it as it is clearly designed as a fun IEM and I really love it for that purpose with its extremely well-made implementation of the emphasis on both ends).
Spatial closeness and mellowness are a bit better conveyed by the NS-U1 both with disabled and enabled NatroSound, with the overall somewhat larger soundstage as well. It’s basically more or less a tie, with one aiming for more fun and the other for more naturalness and balance (-> it’s up to one’s personal preference).

LEAR LHF_AE1d (with upgrade nozzles):
That this wouldn’t be an easy comparison was quite clear right from the beginning, as the LHF-AE1d is one of the best, most versatile and natural sounding dynamic driver in-ears in my book – although it doesn’t reach my Sennheiser IE 800’s technical level (especially in terms of bass speed and separation), the LEAR sounds more convincing, more natural and has got the more realistically sounding midrange and treble, with the spatially more circular soundstage and a level of midrange and treble details that doesn’t lack too much behind the Sennheiser’s at all. Hence, at around $200 in the category of the single-driver dynamic in-ears, the LEAR is my reference.
The NS-U1 sounds more direct in the middle treble compared to the LHF-AE1d (which has got a relaxed-gene dip here).
The NS-U1’s bass is tighter, faster and with the better control, but the AE1d features the even higher resolution in the midrange and treble. Additionally, it also sounds even more natural and realistic. As a result, the AE1d still remains “the king” in the category of dynamic driver in-ears around $200.
With disabled NatroSound, both in-ears’ soundstage is about equally good in my ears. With activated NS however, the NS-U1 conveys the better impression of proximity, but also slightly loses some points of spatial precision.

Conclusion:

The NS-U1 doesn’t make me a total crossfeed devotee (at least with the standard cable NSC-01, as the NSC-03 offers the better-made spatial presentation to my ears) and doesn’t completely offer the crossfeed quality of ifi Audio’s implementation, but the NatroSound effect is better distinguishable and doesn’t only make the soundstage appear somewhat more distant, but also gives the better impression of proximity at the same time, which can be mainly heard by more intimate voices. With some recordings, the soundstage does indeed appear more natural (especially with old as well as newer, synthetically produced tracks), with others however the spatiality remains identical (but with a “different” appearance), and with some the spatial impression is somewhat inferior – it totally depends on the recording. What I have however noticed on myself is that, with enabled NatroSound, I experience less listening fatigue when listening over a longer period of time, even despite the more prominent fundamental range with the NSC-01 cable – it seems like the perception inside of my brain with enabled NS is quite close to the perception of real environment, wherefore my brain gets less strained, with less listening fatigue after longer sessions as a result.

Desirable would be somewhat less fundamental warmth with the NSC-01 cable with engaged NatroSound – as the mids are without NS, their sound is very balanced and natural, however they sound somewhat too warm and a bit veiled as well with activated NatroSound. With the NSC-03 cable however, this can be regulated much better and the fundamental warmth can be reduced to the extent of not being present as long as the NS potentiometer isn’t fully engaged – generally, I would highly recommend the optional NSC-03 cable anyway, as it doesn’t only give one the ability to adjust the NatroSound driver’s intensity to one’s liking but also to add or subtract bass and fundamental warmth without enabled NS. Besides all of that, I also perceive the NSC-03 cable’s spatial presentation with engaged NatroSound to be more natural and with the better instrument placement (when the pot isn’t turned to the max. position).

The NS-U1 is a unique in-ear and on a qualitatively good level for in-ear headphones with dynamic drivers, sporting quick and well controlled lows and sounding mostly natural. In addition, the NatroSound ability reduces listening fatigue.

All in all, I give the NS-U1 with the NSC-01 cable 3.9 out of 5 and with the NSC-03 cable 4.7 out of 5 possible stars – in average, this makes 4.3 out of 5 stars.

Last but not least, here are a few suggestions to Tatco: better mouldable memory wire on the cable, a cable cinch (chin-slider) on the NSC-01 cable as well as a remote control on the NSC-03 cable would be handy.